Fan wheel



March 15, G- G, CURRIE A FAN WHEEL Filed March 7, 1921 2Sheets-Sheet 'Li .i w )l 02/ Curre MneJJ: Q

v 1,620 875 March 15, 1927. G. G. CURRIE g FAN WHEEL Filed March '7.1921 2 Sheets-Sheet 2 :l-'i317 lwenfor faz/ Currie Patented Mar. l15,1927.

GAIL G. CURBIE, 0F LOS ANGELES, CALIFORNIA.

FAN WHEEL.l

application med March 7, v1921. serial No. 450,289.

This invention relates to exhaust fan wheels for moving large volumes ofnonliquid fluids.

An object of the invention is to increase the efficiency of fans of thatcharacter.

Fans of this character are driven by belt drive or directconnectedmotors and for the purpose of this description, it will be shown as'constructed to be direct -driven by an electric motor. The fan may bepositioned in any manner desiredv and which is best adapted for theservice required; and lts axis. of revolution may extend in anydirectlon.

Certain terminology relating to the fan yis thereforel somewhatarbitrary in the present specification and claims, and, to avoidconfusion, certain directions relative to the vfan and the translationof motion are termed as follows:

Onward signifies the direction in which` the current of air is driven by the fan; front signies the surface the air leaves 1n its onwardcourse; back and backward 1ndicates the opposite offront and onward;4

forward refers to the direction the blades of the fan move relative tothe edges, surfaces or parts of the blades that out the air; rearwardand rearwardly signi'fy the opposite direction of forward; center andinner rel fers to the portion of the fan adjacent the hub; and outer,the direction and locus away from the hub.

This invention is broadlyI new', basic and pioneer in that'the fan wheelcomprises fan blades having dentated forward edges and having frontfacesv formed with loops or cavities, the front ioors of which slo efrom the dentations onwardly,'forming yetween Y said dentations achannel at the back of the blade so that air pressure on the back of theblade will be supplied to the back of both of the loo s from theadjacent edges of the loops.; an I have found by experiment that. themost etl'ective place at which to locate said channel, is about a, halfto two-thirds of the way from the rim to the hub of the wheel. `By `thisconstruction,l the tendency to vacuum produced by each revolving bladewill be supplied more readily and directly, and the resistance torevolution Aof the wheel is thereby decreased.

By this construction, the wheel is pro-v vided with an inner and anouter circle orV set of outwardly and onwardly diminishing loops havingfloors that slope onward from the air cutting edge, and onward in thedij rection of air propulsion, the tloorsotl ther the blade, and todrive it forward at agreater initial velocity than would be given if thefloor was at a less angle than the floors of the outer set of cavities.

By this novel construction and arrangement, the'volume of air drivenonward at the central part of the wheel is increased, and, a greatervolume of air will be driven onward by a predetermined amount ot' powerthan with former fan wheels.

The inner loops of greater pitch ser've to offset the decrease inperipheral velocity at. the shorter radius, thus moving onward a greateramount of air with a minimum expenditure of horsepower. 4

In common practice the blades mayor may not extend to the hub of thewheel.

An. object of this invention is to make provision whereby the tendencyof the fan y 4 lades to create a vacuum behind the blades will be offsetby a full supply of air under atmospheric pressure to the back of theblades in the most efiicient manner; and this I accomplish by providingan abrupt rearward oli'set or detent Yin the front edge of the bladenear the inner end thereof and producing a loop extending from saidoilset to the rear edge of the blade so that the bottom of the loopoperates as an air propelling element arranged at a more abrupt anglethan the outer portions of the blades thus to increase the volume-andvelocity of the air moved onward bythe blades near thel center of thewheel.

The angle of the rear face of theblade; at i the junction of the offset.vwith the main body of the blade forms a backA channel to receiveatmospheric air and to distribute it over the back of the blade on bothsides ot'- said channel extending from the forward to eliminating anyretardation of the motor by reasons of vacuum atthe back of the blades.The inventlon includes the combination with the outer curved pockets ofthe fanpick up air at a peripheral speed lower than that of the rim ofthe wheel. t,

Other objects, advantages and features ofinvention may appear from theaccompanying drawing, the subjoined detail description and the appendedclaims.

The accompanying drawing illustrates the invention.

Figure 1 is a fragmental section on line indicated at x1, Figs. 2 and 3,showing the fan attached toa. motor.

Fig. 2 is a reduced rear view of the fan detached from the motor andsupport.

Fig. 3 is a front view of the fan shown in Fig. 2. y

Figs. 4, 5 and 6 are sect-ions on the respective lines m4, m5, and ai,Fig. 3, looking in the direction of the arrows, respectively.

Fig. 7 is a view of a blank `from which `one of the direct blades may bebent up.

Fig. 8 is a detached View of a blade formed by bending up the blankshowir in Fig. 7.

The fan A is mounted in a suitable frame near the hub and form an outerdetent a and an air impelling surface b sloping to the plane of the rim8, and the contour of the back c and also the forward cutting edge l ofeach blade is broken by the loop e; the cutting edge f of which islocated so far from the rear edge that the pitch of the loop e from itscutting edge f to the rear edge g is at a greater angle to the plane ofrotation than is the floor of the outer loop and there is a channel 11at the back of the blade between the loops. The bottom 13 of the loop eextends or slopes backward and onward so as to produce a current of airin the onward direction; that is, away from the motorin parallelism withthe axis of rotation, and increases the volume of the onwardly propelledcurrent of air. I have provided the direct blades of my fan with loopeddentate forward edges, the loops constituting depressed portions a, d, eand f, the loops e, f having side walls 11 and 12 and bottoms 13 slopingfrom their front retracted edges d, and f rearwardly with relation tothe direction in which the wheel rotates and onward in the diiection ofthe current of air, the loops or dentations f, thus formingsupplementary air impelling faces at a greater angle to the plane ofrotation, than the main bodies 9 of the blades.

By v.this construction the fan blades are adaptedvto cause aconsiderable increase in the volume and velocity of the current of freeair amounting to -about 25%, more or less.

The parts 14 act as braces to the blades 9, and increase the rigidity oftheir attachment tothe spokes. By this construction and arrangement, achannel 15 is provi-ded on the back of the blades at the meeting edgesof the loops; and as the fan wheel rotates, the forward points `of thedentated edges of the blades cut the air before the edge of the backchannel 15 so that air is allowed to flow to the inner portion of theback face of the outer loop and on the outer portion of the back face ofthe inner loop, thus allowing air pressure to be applied over the backof the blades from an intermediate point, .thus relieving the vacuummore completely than has heretofore been the case in fan wheels.

In practical operation the fan wheel is rotated in the directionindicated by the large curved arrows in Figs. 2 and 3. The direct bladeswith ltheir outer and inner loops aand f drive the air onward withmarked increase over blades not having the inner pockets.

In the drawings the outer loops are shownas extending about two-thirdsof the way from the rim toward the hub and the channels 15 between theloops a and f extends from the forward eedges of the blades to rearwardedges respectively. It is thus seen that I have not only succeeded inincreasing the volume of air impelled by the wheel, buthave alsodelivered the vacuum at the back of the wheel, thus taking a measure ofstrain ofi" of the shaft.

I claim:

1. A fan wheel comprising fan blades the rear edges of which are in acommon plane and the forward edges and front fans of which blades areformed with dentations; the forward faces of said blades beingrespectively formed with outer and. inner loops and there heiligchannels at the backs of the blades between the dentations and loops.

2. A fan Wheel comprising a rim, a hub, and radial spokes between thehub and rim; and alsol comprising fan blades, the rear edges of whichare fixed to the spokes respectively, and the forward edgesof whichblades are formed with dentations; the forward faces of said bladesbeing respectively formed in loops sloping onward respectively from thedentations to the plane of the spokes and rim.

3. A fan lwheel comprising a rim, a hub, and radial spokes between thehub and rim; and also comprising fan blades, the rear edges of which arefixed to the spokes respectively, and the forward edges of which bladesare formed with major and minor dentations; the forward faces of saidblades being respectively formed in major and minor loops sloping onwardrespectively from the major and minor dentations to the plane of thespokes and rim.

4. A fan wheel comprising a rim, a hub, and radial spokes between thehub and rim; and also comprising fan blades, the rear edges of which arefixed to the spokes respectively, and the forward edges of which bladesare formed with dentations; the forward faces of said blades beingrespectively l'orined in loops sloping onward respectively from thedeutated edges to the spokes and to the plane of the rim; said lnajordentations and loops occupying approximately two-thirds of the spacebetween the rim and hub of the wheel.

A fan wheel coinprising'a rim, av hub, and radial spokes between the huband rim; and also comprising fan blades, the rear edges of which arefixed to the spokes respectively,` and the forward edges of which bladesare formed with dentations; the for ward faces of said blades beingrespectively formed in loops sloping onward respectively from thedentated edges to the spokes and to the plane of the rim, said majordentations and loops occupying approximately two-thirds of the spacebetween the rim and hub of the wheel; and the pit-ch of the floors ofthe loops being greater than that of the lioors of the major loops.

(i. A fan wheel provided with sheet metal blades, the front edges ofwhich are bowed rearwardly for a distance from the rim and then returnedapproximately to the plane produced from the rim and there pro videdwith a rearward offset to pick up the air near the hub of the wheel; therear edge of the blade beingy practically straight and in the said planeof the rim ofthe blade.

7. A fan wheel comprising a rim, a hub, and radial spokes between thehub and rim; and also comprising fan blades, the rear edges of which arefixed to the spokes respectively, and the forward edges of which bladesare formed with major and minor rearwarddentations; the forward faces ofsaidblades being respectively formed with major and minor cavitiesextending'respectively from the major and minor dentations to the planeof theI spokes and rim, saidniajor dentations and c'oncavities`extending approximately two-thirds of the distance from rim to hub ofthe wheel.

8. A revolving fan` wheel in w-hich the front edgesv of the blades areoffset near the axis of revolution.

9. A fan wheel comprisingy fan blades y Garn G. CURRIE.

